The present invention relates to a method for constructing a large structure, such as a heat exchange tower, and apparatus for use in such construction method.
More particularly, the present invention relates to a method for constructing a structure that, when constructed, is too large to transport using typical transportation methods such as the highways or railways. Otherwise, the structure could simply be made offsite and transported by rail or truck to the desired location whenever it is needed. There are many typical structures that are field-erected because they are too large to transport by highways or railways. Examples of such structures include heat exchange apparatus, and by way of further example cooling towers and the like, water treatment structures, large water or other liquid or gas storage structures, industrial, commercial or residential buildings, especially those constructed from subassemblies or modules, and any number and type of other large structures. These structures are typically constructed in the place where they are needed to operate and function.
Such structures are often used to replace similar existing structures in locations such as power plants, water treatment plants, refineries, hospitals, or other industrial or commercial operations. When the structure is replacing an existing structure, or is otherwise being incorporated into an existing system containing other components, it is critical to minimize downtime during initial and replacement construction of structures associated with the ongoing operations. Thus, for example, at a power plant, if heat exchange apparatus, such as a cooling tower, were not able to be replaced quickly, substantially the entire power plant would have to be shut down and either critical services provided by the power plant would not be available or such services would have to be provided by other operators elsewhere. While sometimes portable equipment can be used temporarily to sustain some level of operation, typically on a reduced scale, the lost time and associated revenue involved with the construction clearly must be minimized.
The present invention reduces such downtime significantly and allows for construction in a nearby, preferably adjacent, site of the structure to be built while a site is being readied or to allow time to dismantle and remove an original structure to be replaced. In this way, construction of the new structure can occur at the same time as the old structure is being dismantled, and when the desired site is available, the new structure can be readily moved to the site, final construction details taken care of and the industrial or commercial operation requiring the use of the structure can begin promptly.
The present invention also involves apparatus in the form of a lift platform that may be used with the method of construction according to the present invention. The lift platform, preferably made of subassemblies as described below, may be lifted by a movable hoist, such as a crane, or even an aircraft such as a helicopter, connected to the structure to be moved from a first location where the structure is being constructed to a second location, which is the ultimate, desired location. The lift platform is sufficiently strong and balanced to be able to lift the structure and move it without damage, including damage either to its framework or to any of the internal components of the structure that are being assembled within the structure at the first location so that there is less work to be done in finishing the construction of the structure at the second site.
As used herein, the singular forms “a”, “an”, and “the” include plural referents, and plural forms include the singular referent unless the context clearly dictates otherwise.
As used herein, the term “field-erected” with respect to the type of structure to be constructed, lifted and moved according to the present invention means a structure of any type that is too large to be moved using rail or highway transportation due to the size of the structure exceeding the limits imposed for rail or highway transportation.
Certain terminology is used in the following description for convenience only and is not limiting. Words designating direction such as “bottom,” “top,” “front,” “back,” “left,” “right” and “sides” designate directions in the drawings to which reference is made, but are not limiting with respect to the orientation in which the invention and its components and apparatus may be used. The terminology includes the words specifically mentioned above, derivatives thereof and words of similar import.
As used herein, the term “generally” or derivatives thereof with respect to any element or component means that the element or component has the basic shape, direction, orientation or the like to the extent that the function of the element or component would not be materially adversely affected by somewhat of a change in the element or component. By way of example and not limitation, where generally perpendicular braces are oriented generally perpendicularly between and connected at opposite ends to transverse lift beams, the braces can be oriented a few degrees more or less than exactly 90° with respect to the beams such that the braces and beams still would be “generally perpendicular” with respect to each other, where such variations do not materially adversely affect the function of the element, component of the subassembly or assembly of which the element or component is a part or with which it is used.
As used herein, the term “ground-based,” with respect to a description of a movable hoist, means that the hoist is directly connected or indirectly connected to the ground, as by an intermediate connection to a portion of a support or building or to a vehicle like a mobile crane supported by the ground, to a vessel supported by water or to an underwater structure. This is as opposed to a hoist that is connected to some type of aircraft, such as a helicopter, that during lifting has no direct or indirect connection to the ground. The movable hoist is “movable” by virtue of the hoist having the ability to lift and move the structure from a first location to a second location, even if it is just by lifting and swiveling from a fixed base position, as well as also by traversing across the ground or water.
As used herein, the term “horizontal,” derivatives thereof and words of similar import, with respect to the orientation of an element or component of any element relating to the present invention, means the generally horizontal direction or orientation, that is generally, but not necessarily absolutely parallel to the ground, or not necessarily absolutely perpendicular to a vertical or upright direction, when the element or component is erected as a part of an assembly or subassembly of a structure, rather than in an unerected or unassembled state or condition.
As used herein, the term “vertical,” derivatives thereof and words of similar import, with respect to the orientation of an element or component of any element relating to the present invention, means the generally vertical or upright direction or orientation, that is generally, but not necessarily absolutely perpendicular to the ground, when the element or component is erected as a part of an assembly or subassembly of a structure, rather than in an unerected or unassembled state or condition.